Body mass index of inpatients with schizophrenia in Japan.

Objective: Many studies reported that obesity rate in the Western countries is higher in schizophrenia patients than in general population. In this study, we surveyed nationwide Body Mass Index (BMI) status of hospitalized Japanese schizophrenia patients.

Methods: Subjects included 15,171 patients (7,897 men and 7,274 women) hospitalized for schizophrenia, who were sampled from all 47 administrative divisions in Japan. The BMI data of these patients were compared to those of the general population in the 2009 National Health and Nutrition Survey conducted by the Japanese Ministry of Health.

Results: The median BMI value in the patients was 21.6 kg/m2 (first quartile, 19.1; third quartile, 24.5). The percentages of BMI in obese, normal-weight, and underweight patients were 21.6%, 58.2%, and 20.2%, respectively. In the Japanese male patients, frequency of obesity was lower, and underweight was higher than those in the general population. In female patients, frequency of both obesity and underweight were higher than those in the general population.

Conclusions: Our results provided evidence that underweight as well as obesity is a characteristic in Japanese schizophrenia inpatients.